The Transneptunian Automated Occultation Survey (TAOS II) Matthew Lehner ASIAA

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1 The Transneptunian Automated Occultation Survey (TAOS II) Matthew Lehner ASIAA

2 Academia Sinica Institute of Astronomy and Astrophysics Universidad Nacional Autónoma de México Harvard-Smithsonian Center for Astrophysics National Research Council Canada

3 Direct searches well-suited to objects larger than R ~30 km Occultations of bright stars can reveal smaller and/or more distant objects No orbital information Can measure inclination distribution if enough events.

4 Scientific Objectives: Measure faint end size distribution of Kuiper Belt o Dynamical evolution o Structure of objects Determine source of Jupiter Family Comets Technical Objective: Detect objects that can be observed directly by large ground-based telescopes o Confirm survey results o Estimates of albedos Factor of 100 improvement in sensitivity over TAOS I

5 Occultation Events Fresnel Scale: F / 2 F a / 2 F = 1.5 km at 43 AU Minimum event width: W 2 3F 5 km Objects in relative motion, v ~ 25 km/sec at opposition Event timescale ~200ms! 10 km

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7 Requirements: Photometrically monitor >10,000 stars simultaneously Event rate <0.001/star/year 1.3m F/4 wide field telescopes. R lim = 18.5 (SNR = 1.2) High speed imaging Event duration ~200 ms, significant diffraction: 20 Hz sampling rate Custom CMOS imagers: multiple sub-frame readout Minimize false positive rate Require coincident detection in multiple telescopes Telescopes separated by >100m to minimize false positives from scintillation Three identical telescope systems separated by 130m to 320m

8 San Pedro Mártir More than 290 clear nights per year Good seeing (median 0.57 arc sec.) Dark sky V: 21.5 mag/sq. arc sec. R: 20.7 mag/sq. arc sec. Light pollution ordinance in effect for Baja California Working on same for Baja California Sur, Sonora

9 San Diego Tijuana Mexicali Yuma Ensenada 175 km OAN-SPM 55 km San Felipe 2014 Google, INEGI credit: NASA s Earth Observatory

10 Site 266m 323m 127m

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12 Current Status Site construction began 2013 September Access roads completed 2013 November Power installation to sites completed 2014 August Construction of enclosures completed 2017 April Domes installed 2017 August Network installed 2017 November Site Development Complete!

13 Telescopes Three telescopes from DFM Engineering F/4 1.3m modified Richey Chretien Single Schmidt corrector plate F/4 version of OGLE telescope 1.7 FOV over 154 mm diameter 80% energy within 0.8 on axis, 1.0 at edge of field <1 arcsec open loop tracking error over 20 minutes 5 axis focus housing Telescopes installed 2017 October

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15 Cameras Data Rate: 88 Mpix camera (3 of them) 20 Hz readout 250 TB of raw image data per night! Sub-aperture readout Image data rate a factor of 200 lower 3-4 TB/night image + light curve data Nearly 1 PB per year!

16 Cameras Custom CMOS imagers from e2v µm pixels 3-edge buttable Back illuminated 100% photosensitive! Readout on multiple sub-frames (>1200 per imager) Onboard correlated double sampling (CDS) Read noise 2.7 e - Focal plane comprised of 2 5 array of imagers

17 Custom CMOS devices from e2v (CIS 113) 9/26/2016 EAMA 10 meeting

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19 Prototype camera

20 LED image from prototype camera

21 High-Speed Sub-Window Mode

22 High-Speed Sub-Window Mode

23 Data management 3-4 TB/night image and light curve data Approaching 1 PB/year! Data storage HDF5 One file for each star per 2 hour data run 7 pixel 7 pixel 3 telescope 144,000 epoch hypercube Database with all file locations, metadata, weather, etc. Using TAOS I as test bed Storage facilities Mexico (Ensenada) US$175k for data center, 500 TB. NRC in Canada Funding in place for 5 PB of storage at CADC Taipei?

24 Schedule Science cameras delivered 2018 March 1 2 months for commissioning Survey begins Summer 2018 Nominal survey duration of 5 years May run longer (or shorter) depending on event rate

25 Other science Variable stars Exoplanet transits Probably not GRB follow-up Already several telescopes at SPM dedicated to this science

26 Future Plans Telescope installation part of long term development strategy for ASIAA New science goals after completion of TAOS II survey TBD Time domain science a likely possibility New instruments? Multi-color observations?